The present invention is directed, in general, to retractable blade utility knives and, more specifically, to a utility knife having an improved retractable blade carrier structure and method of manufacturing the same.
Utility knives are specialty knives used throughout various industries to meet a wide range of needs. Some of these needs include cutting tough materials (such as carpet) or strapping surrounding crates, boxes or cartons. However, utility knives are perhaps most commonly used for opening the boxes and cartons themselves.
Both fixed blade and adjustable blade utility knives are well known in the art. However, a significant problem for those who use utility knives arises from the lack of positioning control found in conventional utility knives. Specifically, the knife-holding heads found on prior art utility knives in the prior art fail to maintain positional control of the blade during use. As a result, the knife-holding head in such utility knives have a tendency to wander from the cutting path intended by the worker. This can cause the knife-holding head to wander during cutting of a carton, perhaps such that the products contained in the box are damaged. Moreover, wandering could cause the blade to veer away from the surface to be cut, resulting in the blade cutting an object, or even a person, rather than the intended material.
In addition, prior art utility knives also often fail positively to secure the blade itself in place. Although some prior art utility knives and blades have corresponding notches or apertures to assist in keeping the blade in place, some amount of blade movement inevitably occurs during cutting. Even slight movement of a blade during cutting can cause the blade to chip, crack or completely break when it is inserted into a tough material. As a result, safety issues, the cost of replacing damaged goods and the added cost of replacing chipped or broken blades become significant concerns.
Accordingly, what is needed in the art is a utility knife having an improved retractable blade carrier structure that overcomes the disadvantages of the prior art utility knives described above. In addition, what is needed in the art is a method of manufacturing such a utility knife.
To address the above-discussed deficiencies of the prior art, the present invention provides a utility knife and various manufacturing methods for the utility knife. In one embodiment, the utility knife includes: (1) a body having a cutting face and (2) a blade-holding slide mounted for linear movement within the body and having a knife-holding head extendable through an opening in the cutting face. The opening has aparallel opposing sides that diverge toward a cutting direction of the utility knife. The knife-holding head has corresponding aparallel opposing sides that cooperate with the sides of the opening to cause a cutting force exerted on the knife-holding head to wedge the blade-holding slide within the opening and thereby stiffen the knife-holding head with respect to the body during operation of the utility knife. In one embodiment of the present invention, the blade-holding slide resiliently urges the knife-holding head to unwedge when the cutting force is removed therefrom.
In one embodiment of the present invention, the blade-holding slide and the body have a plurality of cooperating detents located on adjoining surfaces thereof and the utility knife further comprises a locking release button, passing through a rear surface of the body, that separates the plurality of detents to allow the blade-holding slide to move linearly with respect to the body. In a related embodiment, the blade-holding slide and the body have a plurality of cooperating detents located on adjoining surfaces thereof, the blade-holding slide resiliently maintaining the plurality of cooperating detents in an engaged position to prohibit linear movement of the blade-holding slide with respect to the body.
In one embodiment of the present invention, the utility knife may further include locking and locking release buttons passing through opposing sides of the body and adapted to engage the blade-holding slide, the locking button activatable to cause the blade-holding slide to lock positively with respect to the body, the locking release button activatable to displace the blade-holding slide laterally and allow linear movement of the blade-holding slide with respect to the body only when the locking button is disengaged.
In one embodiment of the present invention, the body has a rear end portion distal from the cutting face that is hooked and configured for holding a fixed blade oriented for cutting a strap. The strap-cutting feature is not required, however.
In one embodiment of the present invention, the utility knife further includes a spring loaded knife guard extending from a second opening in the cutting face proximate the knife-holding head. The knife guard advantageously deflects objects (such as human digits) away from the cutting edge of a knife blade when the cutting face is not deliberately pressed against a surface to be cut.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.